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use alloc::fmt;
use core::num::NonZeroU16;
use serde::{Deserialize, Serialize};
pub type Speed = NonZeroU16;
#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
pub enum SpeedValue {
/// Speed in kilometers per hour
Kmh(Speed),
/// Speed in miles per hour (Multiply by 1.609344)
Mph(Speed),
/// Speed in knots (Multiply by 1.852)
Knots(Speed),
/// No speed limit (typically represented as "none" in OSM)
None,
/// Variable speed limit (electronic signs, etc.)
Variable,
/// Speed limit is inherited from a higher-level way/relation
Inherited,
/// Walk speed (typically 5-6 km/h)
Walk,
}
impl SpeedValue {
/// Shows the speed as represented in Kilometers per Hour.
pub fn in_kmh(&self) -> Option<Speed> {
match self {
SpeedValue::Kmh(speed) => Some(*speed),
SpeedValue::Mph(speed) => {
Some(NonZeroU16::new(((speed.get() as f64) * 1.609344) as u16)?)
}
SpeedValue::Knots(speed) => {
Some(NonZeroU16::new(((speed.get() as f64) * 1.852) as u16)?)
}
// Non-transformative
_ => None,
}
}
/// Parses a speed value from a given speed-string.
/// An example value might be `50 mph`. In which case,
/// the returned value must be `Some(Mph(50))`.
///
/// To convert/standardise a speed value, you may use
/// the `in_kmh(..)` function to represent the speed
/// value in kilometers per hour.
pub fn parse(value: String, unit: String) -> Option<Self> {
let numeric = value.parse::<Speed>().ok()?;
Some(match unit.as_str() {
// Numeric units
"mph" => SpeedValue::Mph(numeric),
"kph" => SpeedValue::Kmh(numeric),
"knots" => SpeedValue::Knots(numeric),
// Non-numeric
"variable" => SpeedValue::Variable,
"inherited" => SpeedValue::Inherited,
"none" => SpeedValue::None,
"walk" => SpeedValue::Walk,
// Unspecified, by default, is kph
_ => SpeedValue::Kmh(numeric),
})
}
}
impl fmt::Display for SpeedValue {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
SpeedValue::Kmh(speed) => write!(f, "{speed}"),
SpeedValue::Mph(speed) => write!(f, "{speed} mph"),
SpeedValue::Knots(speed) => write!(f, "{speed} knots"),
SpeedValue::None => write!(f, "none"),
SpeedValue::Variable => write!(f, "variable"),
SpeedValue::Inherited => write!(f, "inherited"),
SpeedValue::Walk => write!(f, "walk"),
}
}
}